• 천문학회보
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• 제42권1호
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• pp.51.3-51.3
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• 2017

To investigate the connection between radio activity and AGN outflows, we present a study of ionized gas kinematics by using [O III] ${\lambda}5007$ emission line along the radio jet for six radio AGNs. These AGNs are selected based on the radioactivity (L1.4GHz ${\geq}$ 1039.8 erg s-1) as well as optical properties as type 2 AGNs. By using the high spatial resolution of the Red Channel Cross Dispersed Echellette Spectrograph at the Multiple Mirror Telescope, we investigate in detail the [O III] and stellar kinematics. We spatially resolve and probe the central AGN-photoionization sizes, which is important in understanding the structures and evolutions of galaxies. We find that the typical central AGN-photoionization sizes of our targets are in range of 1.8-3.8 kpc. We study the [O III] kinematics along the radio jets to test whether there is a link between gas outflows in the narrow-line region and radio jet emissions. Contrary to our expectation, we find no evidence that the gas outflows are directly connected to radio jet emission.

• 천문학회보
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• 제43권1호
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• pp.63.4-64
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• 2018

High resolution spectroscopy of the yellow symbiotic star AG Draconis is performed with the Canada-France-Hawaii Telescope to analyse the line profiles of Raman scattered O VI broad emission features at $6825{\AA}$ and $7082{\AA}$ with a view to investigating the wind accretion process from the mass losing giant to the white dwarf. These two spectral features are formed through inelastic scattering of O $VI{\lambda}{\lambda}32$ and 1038 with atomic hydrogen. We find that these features exhibit double-component profiles with red parts stronger than blue ones with the velocity separation of ~ 60 km s-1 in the O VI velocity space. Monte Carlo simulations for O VI line radiative transfer are performed by assuming that the O VI emission region constitutes a part of the accretion flow around the white dwarf and that Raman O VI features are formed in the neutral part of the slow stellar wind from the giant companion. The overall Raman O VI profiles are reasonably fit with an azimuthally asymmetric accretion flow and the mass loss rate ~ 4 ${\times}$ 10^{-7} M_sun yr^{-1}. We also find that additional bipolar neutral regions moving away with a speed ~ 70 km s^{-1} in the directions perpendicular to the orbital plane provide considerably improved fit to the red wing parts of Raman features.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.360-368
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• 1999

The paper describes spectroscopic characteristics of plasma induced in the pulsed YAG laser welding of alloys containing a large amount of volatile elements. The authors have conducted the spectroscopic analyses of laser induced Al-Mg alloys plasma in the air and argon atmosphere. In the air environment the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn and singly ionized Mg lines as well as the intense molecular spectra of ALO and MgO formed by chemi-cal reactions of evaporated Al and Mg atoms from the pool surface with oxygen in the air. In argon atmosphere MgO and AlO spectra vanished but AlH spectrum was detected. the hydrogen source was presumable hydrogen dissolved in the base metals water absorbed on the surface oxide layer or $H_2$ and $H_2O$ in the shielding gas. The resonant lines of Al and Mg were strongly self-absorbed in particular self-absorption of the Mg line was predominant. These results show that the laser induced plasma was made of metallic vapor with relatively low temperature and high density.

• 한국산업정보학회논문지
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• 제23권5호
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• pp.33-41
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• 2018

Most important thing when designing and implementing a supply chain network is to consider various problems which may occur in real world situation. In this paper, we propose a supply chain network considering two problems (environmental factor and transportation types) under real world situation. CO2 emission amount as environmental factor is considered since it is usually generated from production and transportation processes. Normal delivery, direct delivery and direct shipment as transportation types are also considered since many customers ask various transportation types for delivery or shipment of their products under on-line or off-line purchase environment. The proposed supply chain network considering environmental factor and transportation types is represented in a mathematical formulation and implemented using hybrid genetic algorithm (HGA) approach. In numerical experiments, several scales of supply chain networks are presented and implemented using HGA approach. The performance of the HGA approach is compared with those of some conventional approaches under various measures of performance. Finally, it is proved that the performance of the HGA approach is superior to those of the others.

• Journal of Information Display
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• 제5권4호
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• pp.18-22
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• 2004

A carbon nanotube field emission display (CNT FED) panel with a 2 inch diagonal size was fabricated through screen printing of a prepared photo-sensitive CNT paste and vacuum in-line sealing technology. After surface treatment of the patterned CNT, only the carbon nanotube tips are uniformly exposed on the surface. The diameter of the exposed CNTs are usually about 20nm. The sealing temperature of the panel is around 390 $^{\circ}C$ and the vacuum level is obtained with $1.4{\times}10^{-5}$torr at the sealing. The field emission properties of the diode type CNT FED panel are characterized. Currently, we are in the process of developing a triode type CNT FED with a self-aligned gate-emitter structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.464-466
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• 2001

In this paper, we developed the on-line Data Aquisition System(DAS) of distribution transformers using the hardware and monitoring program. The DAS consists of the top oil temperature sensing part, ambient temperature sensing part, load current sensing part, acoustic emission peak-value sensing part, acoustic emission pulse counter part, micro-processor part and wireless communication part. The Monitoring System consists of the communication setting, online monitoring and database construction part. The DAS send the data acquired from the some sensors of the distribution transformers to the host PC. The monitoring program of the host PC stores the data to database. And the monitoring system estimates the loss of life time for distribution transformer from the DB. Thus, it could be managed the career and the functional lifetime of the transformer more efficiently than existing methodologies.

• 천문학회보
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• 제39권1호
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• pp.40.2-40.2
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• 2014

The connection between the active galactic nuclei (AGNs) and star formation activity is one of the most important issues in understanding the coevolution of supermassive black holes (SMBHs) and galaxies. In our recent study, by using SDSS quasar spectra we found that the emission-line flux rations involving a nitrogen line, i.e., $NV{\lambda}1240$, correlate with the Eddington ratio. This correlation suggests that the mass accretion into SMBH is associated with a post-starburst phase, when AGB stars enrich the interstellar medium with the nitrogen. Moreover, we focused on nitrogen-loud quasars, which have prominent emission lines of the nitrogen, to investigate whether this argument is correct or not. We will present our recent results described above and discuss the relation between the star formation and feeding to SMBHs.

• 천문학논총
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• 제30권2호
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• pp.443-445
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• 2015

We provide results of near-infrared (NIR) spectroscopic observations of 83 nearby (0.002< z <0.48) and bright (K <14 mag) type 1 active galactic nuclei (AGNs). For the observations, we used the Infrared Camera (IRC) on AKARI allowing us to obtain the spectrum in the rarely studied spectral range of $2.5-5.0{\mu}m$. The $2.5-5.0{\mu}m$ spectral region suffers less dust extinction than ultra violet (UV) or optical wavelength ranges, and contains several important emission lines such as $Br{\beta}$ ($2.63{\mu}m$), $Br{\alpha}$ ($4.05{\mu}m$), and polycyclic aromatic hydrocarbon (PAH; $3.3{\mu}m$). The sample is selected from the bright quasar surveys of Palomar Green and SNUQSO, and AGNs with black hole (BH) masses estimated from reverberation mapping method. We measure the Brackett line properties for 11 AGNs, which enable us to derive BH mass estimators and investigate circum-nuclear environments. Moreover, we perform spectral modeling to fit the hot and warm dust components by adding photometric data from SDSS, 2MASS, WISE, and ISO to the AKARI spectra, and estimate hot and warm dust temperatures of ~1100K and ~220 K, respectively.

• Electronic Materials Letters
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• 제14권6호
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• pp.766-773
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• 2018

In this paper, temperature dependence of the excitonic bands in a mechanically exfoliated tungsten diselenide ($WSe_2$) monolayer is studied using photoluminescence and circular dichroic photoluminescence (PL) in the temperature range between 8 and 300 K. The peak energies associated with the neutral exciton (A), charged exciton (trion) and localized excitons are extracted from the PL spectra revealing a trion binding energy of around 30 meV. The circular dichroic PL measured at 8 K shows about 45% valley polarisation that sharply reduces with increasing temperature to 5% at 300 K with photoexcitation energy of 1.96 eV. A detailed analysis of the emission line-width suggests that the rapid decrease of valley polarisation with the increase of temperature is caused by the strong exciton-phonon interactions which efficiently scatter the excitons into different excitonic states that are easily accessible due to the supply of excess photoexcitation energy. The emission line-width broadening with the increase of temperature indicate residual exciton dephasing lifetime < 100 fs, that correlates with the observed rapid valley depolarisation.

• 천문학회지
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• 제55권2호
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• pp.59-66
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• 2022

Stellar magnetic activity is important for formulating the evolution of the star. To represent the stellar magnetic activity, the S index is defined using the Ca II H+K flux measure from the Mount Wilson Observatory. Mg II lines are generated in a manner similar to the formation of Ca II lines, which are more sensitive to weak chromospheric activity. Mg II flux data are available from the International Ultraviolet Explorer (IUE). Thus, the main purpose of this study was to analyze the magnetic activity of stars. We used 343 high-resolution IUE spectra of 14 main-sequence G stars to obtain the Mg II continuum surface flux and Mg II line-core flux around 2,800 Å. We calculated S index using the IUE spectra and compared it with the conventional Mount Wilson S index. We found a color (B - V ) dependent association between the S index and the Mg II emission line-core flux. Furthermore, we attempted to obtain the magnetic activity cycles of these stars based on the new S index. Unfortunately, this was not successful because the IUE observation interval of approximately 17 years is too short to estimate the magnetic activity cycles of G-type stars, whose cycles may be longer than the 11 year mean activity cycle of the sun.